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A002373
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Smallest prime in decomposition of 2n into sum of two odd primes.
(Formerly M2273 N0899)
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31
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3, 3, 3, 5, 3, 3, 5, 3, 3, 5, 3, 5, 7, 3, 3, 5, 7, 3, 5, 3, 3, 5, 3, 5, 7, 3, 5, 7, 3, 3, 5, 7, 3, 5, 3, 3, 5, 7, 3, 5, 3, 5, 7, 3, 5, 7, 19, 3, 5, 3, 3, 5, 3, 3, 5, 3, 5, 7, 13, 11, 13, 19, 3, 5, 3, 5, 7, 3, 3, 5, 7, 11, 11, 3, 3, 5, 7, 3, 5, 7, 3, 5, 3, 5, 7, 3, 5, 7, 3, 3, 5, 7, 11, 11, 3, 3, 5, 3
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OFFSET
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3,1
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COMMENTS
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Note that these primes do not all belong to a twin prime pair. The first instance is a(110) = 23. - Michel Marcus, Aug 17 2020 from a suggestion by Pierre CAMI
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REFERENCES
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D. H. Lehmer, Guide to Tables in the Theory of Numbers. Bulletin No. 105, National Research Council, Washington, DC, 1941, p. 80.
N. Pipping, Neue Tafeln für das Goldbachsche Gesetz nebst Berichtigungen zu den Haussnerschen Tafeln, Finska Vetenskaps-Societeten, Comment. Physico Math. 4 (No. 4, 1927), pp. 1-27.
N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).
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LINKS
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MATHEMATICA
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Table[k = 2; While[q = Prime[k]; ! PrimeQ[2*n - q], k++]; q, {n, 3, 100}] (* Jean-François Alcover, Apr 26 2011 *)
Table[Min[Flatten[Select[IntegerPartitions[2*n, {2}], AllTrue[ #, OddQ] && AllTrue[#, PrimeQ]&]]], {n, 3, 100}] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Aug 31 2020 *)
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PROG
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(Haskell) a002373 n = head $ dropWhile ((== 0) . a010051 . (2*n -)) a065091_list -- Reinhard Zumkeller, Feb 29 2012
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CROSSREFS
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KEYWORD
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nonn,nice,easy
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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